阅读说明：本技术 液晶组合物及其用途、以及液晶显示元件 (Liquid crystal composition, use thereof, and liquid crystal display element ) 是由 森崇徳 朝仓利树 斋藤将之 于 2019-08-19 设计创作，主要内容包括：本发明提供一种液晶组合物及其用途、以及液晶显示元件,所述液晶组合物在上限温度高、下限温度低、粘度小、光学各向异性适当、介电各向异性大、比电阻大、对光的稳定性高、对热的稳定性高之类的特性中,充分满足至少一种特性,或关于至少两种特性而具有适当平衡。本发明的液晶组合物含有选自具有式(S)所表示的一价基的化合物中的至少一种化合物作为第一添加物,也可含有作为第一成分的具有大的正介电各向异性的特定化合物、作为第二成分的具有高的上限温度或小的粘度的特定化合物、或者作为第三成分的具有大的负介电各向异性的特定化合物。(The present invention provides a liquid crystal composition which satisfies at least one of characteristics such as a high upper limit temperature, a low lower limit temperature, a low viscosity, an appropriate optical anisotropy, a large dielectric anisotropy, a large specific resistance, a high stability to light and a high stability to heat, or has an appropriate balance between at least two of the characteristics, a use thereof, and a liquid crystal display element. The liquid crystal composition of the present invention contains at least one compound selected from compounds having a monovalent group represented by formula (S) as a first additive, and may contain a specific compound having a large positive dielectric anisotropy as a first component, a specific compound having a high upper limit temperature or a small viscosity as a second component, or a specific compound having a large negative dielectric anisotropy as a third component.)

1. A liquid crystal composition characterized by: contains at least one compound selected from the group consisting of compounds having a monovalent group represented by the formula (S) as a first additive, and has a nematic phase and positive dielectric anisotropy,

in the formula (S), R^aHydrogen, O, OH, an alkyl group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms, wherein at least one-CH group₂-may be substituted by-O-, -NH-, -CO-, -COO-or-OCO-, at least one-CH₂-CH₂-may be substituted by-CH ═ CH-or-C ≡ C-, at least one of these groups may be substituted by an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, halogen, OH, NHR^1bOr NR^1cR^1dSubstitution; r^1b、R^1cAnd R^1dIs an alkyl group having 1 to 10 carbon atoms.

2. The liquid crystal composition according to claim 1, wherein: containing at least one compound selected from the compounds represented by the formula (1) as the first additive,

in the formula (1), R^bIs hydrogen, fluorine, an alkyl group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms, wherein at least one of the groups-CH₂-may be substituted by-O-, -NH-, -CO-, -COO-or-OCO-, at least one-CH₂-CH₂-may be substituted by-CH ═ CH-or-C ≡ C-, at least one of these groups may be substituted by an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, halogen, OH, NHR^1bOr NR^1cR^1dSubstitution; r^1b、R^1cAnd R^1dAn alkyl group having 1 to 10 carbon atoms; m is a single bond, a tetravalent aliphatic hydrocarbon group having 1 to 20 carbon atoms, or a tetravalent aromatic hydrocarbon group having 6 to 20 carbon atoms, wherein at least one of these groups is-CH₂-may be substituted by-O-or-S-, one or two-CH ═ CH-may be substituted by-CH ═ N-, at least one hydrogen may be substituted by fluorine or chlorine; z^aAnd Z^bA single bond, -O-, -COO-, -OCO-, an alkylene group having 1 to 20 carbon atoms, or an alkenylene group having 2 to 20 carbon atoms, wherein at least one hydrogen may be substituted by fluorine, chlorine, OH; q^aA monovalent group represented by the formula (S); n is 1, 2,3 or 4; m is 4-n; wherein, when M is a single bond, n and M are 1;

in the formula (S), R^aHydrogen, O, OH, an alkyl group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms, wherein at least one-CH group₂-may be substituted by-O-, -NH-, -CO-, -COO-or-OCO-, at least one-CH₂-CH₂-may be substituted by-CH ═ CH-or-C ≡ C-, at least one of these groups may be substituted by an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, halogen, OH, NHR^1bOr NR^1cR^1dSubstitution; r^1b、R^1cAnd R^1dIs an alkyl group having 1 to 10 carbon atoms.

3. The liquid crystal composition according to claim 2, characterized in that: containing at least one compound selected from the group consisting of the compounds represented by the formulae (1-1) to (1-5) as the first additive,

in formulae (1-1) to (1-5), Z^cA single bond, an alkylene group having 1 to 5 carbon atoms, or an alkenylene group having 2 to 5 carbon atoms, at least one hydrogen of which may be substituted with OH; r^cHydrogen, an alkyl group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms, wherein at least one-CH group₂-may be substituted by-O-, -CO-, -COO-or-OCO-, at least one-CH₂-CH₂-may be substituted with-CH ═ CH-or-C ≡ C-, at least one hydrogen of these groups may be substituted with OH, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms; s is an integer from 1 to 20; q^bIs a monovalent group represented by the formula (S-1);

in the formula (S-1), R^dHydrogen, O, OH, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms, wherein at least one hydrogen may be substituted with a halogen.

4. The liquid crystal composition according to any one of claims 1 to 3, characterized in that: the proportion of the first additive is in the range of 0.001 to 2 mass%.

5. The liquid crystal composition according to any one of claims 1 to 3, characterized in that: containing at least one compound selected from the compounds represented by the formula (2) as a first component,

in the formula (2), R^2aIs alkyl group having 1 to 12 carbon atoms, alkoxy group having 1 to 12 carbon atoms, or alkenyl group having 2 to 12 carbon atoms; ring a is 1, 4-cyclohexylene, 1, 4-phenylene, 2-fluoro-1, 4-phenylene, 2, 3-difluoro-1, 4-phenylene, 2, 6-difluoro-1, 4-phenylene, pyrimidine-2, 5-diyl, 1, 3-dioxane-2, 5-diyl or tetrahydropyran-2, 5-diyl; z^2aIs a single bond, ethylene, vinylene, carbonyloxy or difluoromethyleneoxy; x^2aAnd X^2bIs hydrogen or fluorine; y is^2aIs fluorine, chlorine, alkyl of carbon number 1 to 12 with at least one hydrogen substituted by fluorine or chlorine, alkoxy of carbon number 1 to 12 with at least one hydrogen substituted by fluorine or chlorine, or alkenyloxy of carbon number 2 to 12 with at least one hydrogen substituted by fluorine or chlorine; a is 1, 2,3 or 4.

6. The liquid crystal composition according to any one of claims 1 to 3, characterized in that: containing at least one compound selected from the group consisting of the compounds represented by the formulae (2-1) to (2-35) as a first component,

in the formulae (2-1) to (2-35), R^2aIs an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or an alkenyl group having 2 to 12 carbon atoms.

7. The liquid crystal composition according to claim 5, wherein: the proportion of the first component is in the range of 10 to 85 mass%.

8. The liquid crystal composition according to any one of claims 1 to 3, characterized in that: contains at least one compound selected from the compounds represented by the formula (3) as a second component,

in the formula (3), R^3aAnd R^3bIs alkyl group having 1 to 12 carbon atoms, alkoxy group having 1 to 12 carbon atoms, alkenyl group having 2 to 12 carbon atoms, or alkenyl group having 2 to 12 carbon atoms in which at least one hydrogen is substituted with fluorine or chlorine; ring B and ring C are 1, 4-cyclohexylene, 1, 4-phenylene, 2-fluoro-1, 4-phenylene or 2, 5-difluoro-1, 4-phenylene; z^3aIs a single bond, ethylene, vinylidene, methyleneoxy or carbonyloxy; b is 1, 2 or 3.

9. The liquid crystal composition according to any one of claims 1 to 3, characterized in that: contains at least one compound selected from the group consisting of the compounds represented by the formulae (3-1) to (3-13) as a second component,

in formulae (3-1) to (3-13), R^3aAnd R^3bIs an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, or an alkenyl group having 2 to 12 carbon atoms in which at least one hydrogen is substituted with fluorine or chlorine.

10. The liquid crystal composition according to claim 8, wherein: the proportion of the second component is in the range of 10 to 85 mass%.

11. The liquid crystal composition according to any one of claims 1 to 3, characterized in that: contains at least one compound selected from the compounds represented by the formula (4) as a third component,

in the formula (4), R^4aAnd R^4bIs hydrogen, alkyl group having 1 to 12 carbon atoms, alkoxy group having 1 to 12 carbon atoms, alkenyl group having 2 to 12 carbon atoms, or alkenyloxy group having 2 to 12 carbon atoms; ring D and ring F are 1, 4-cyclohexylene, 1, 4-cyclohexenylene, tetrahydropyran-2, 5-diyl, 1, 4-phenylene in which at least one hydrogen is substituted by fluorine or chlorine, naphthalene-2, 6-diyl in which at least one hydrogen is substituted by fluorine or chlorine, chroman-2, 6-diyl in which at least one hydrogen is substituted by fluorine or chlorine, or chroman-2, 6-diyl in which at least one hydrogen is substituted by fluorine or chlorine; ring E is 2, 3-difluoro-1, 4-phenylene, 2-chloro-3-fluoro-1, 4-phenylene, 2, 3-difluoro-5-methyl-1, 4-phenylene, 3,4, 5-trifluoronaphthalene-2, 6-diyl, 7, 8-difluorochromane-2, 6-diyl, 3,4,5, 6-tetrafluorofluorene-2, 7-diyl, 4, 6-difluorodibenzofuran-3, 7-diyl, 4, 6-difluorodibenzothiophene-3, 7-diyl, or 1,1,6, 7-tetrafluoroindan-2, 5-diyl; z^4aAnd Z^4bIs a single bond, ethylene, vinylidene, methyleneoxy or carbonyloxy; c is 0, 1, 2 or 3, d is 0 or 1; and the sum of c and d is 3 or less.

12. The liquid crystal composition according to any one of claims 1 to 3, characterized in that: containing at least one compound selected from the group consisting of the compounds represented by the formulae (4-1) to (4-35) as a third component,

in the formulae (4-1) to (4-35), R^4aAnd R^4bIs hydrogen, alkyl group having 1 to 12 carbon atoms, alkoxy group having 1 to 12 carbon atoms, alkenyl group having 2 to 12 carbon atoms, or alkenyloxy group having 2 to 12 carbon atoms.

13. The liquid crystal composition according to claim 11, characterized in that: the proportion of the third component is in the range of 3 to 45 mass%.

14. The liquid crystal composition according to any one of claims 1 to 3, characterized in that: the upper limit temperature of the nematic phase is 70 ℃ or more, the optical anisotropy at a wavelength of 589nm is 0.07 or more as measured at 25 ℃, and the dielectric anisotropy at a frequency of 1kHz is 2 or more as measured at 25 ℃.

15. A liquid crystal display element, characterized in that: comprising a liquid crystal composition according to any one of claims 1 to 14.

16. The liquid crystal display element according to claim 15, wherein: the operation mode of the liquid crystal display element is a twisted nematic mode, an electric control birefringence mode, an optical compensation bending mode, an in-plane switching mode, a fringe field switching mode or an electric field induced photoreaction orientation mode, and the driving mode of the liquid crystal display element is an active matrix mode.

17. Use of a liquid crystal composition, characterized in that: the liquid crystal composition according to any one of claims 1 to 14 for use in a liquid crystal display element.

Technical Field

The present invention relates to a liquid crystal composition, use thereof, and a liquid crystal display element and the like containing the composition. And more particularly, to a liquid crystal composition having positive dielectric anisotropy, and an Active Matrix (AM) device having a Twisted Nematic (TN), Electrically Controlled Birefringence (ECB), Optically Compensated Bend (OCB), in-plane switching (IPS), Fringe Field Switching (FFS), or electric field induced photoreaction alignment (FPA) mode, which contains the composition.

Background

In the liquid crystal display device, the operation modes based on liquid crystal molecules are classified into Phase Change (PC), Twisted Nematic (TN), Super Twisted Nematic (STN), Electrically Controlled Birefringence (ECB), Optically Compensated Bend (OCB), in-plane switching (IPS), Vertical Alignment (VA), Fringe Field Switching (FFS), field-induced photo-reactive alignment (FPA), and the like. The driving methods of the elements are classified into Passive Matrix (PM) and Active Matrix (AM). The PM is classified into a static type (static) and a multiplexing type (multiplex), etc., and the AM is classified into a Thin Film Transistor (TFT), a Metal Insulator Metal (MIM), etc. TFTs are classified into amorphous silicon (amorphous silicon) and polycrystalline silicon (polysilicon). The latter is classified into a high temperature type and a low temperature type according to the manufacturing process. The light source is classified into a reflection type using natural light, a transmission type using a backlight, and a semi-transmission type using both natural light and backlight.

The liquid crystal display element contains a liquid crystal composition having a nematic phase. The composition has suitable properties. By improving the characteristics of the composition, an AM element having good characteristics can be obtained. The correlation between these properties is summarized in table 1 below. The properties of the composition are further illustrated based on commercially available AM elements. The temperature range of the nematic phase is associated with the temperature range in which the element can be used. The upper limit temperature of the nematic phase is preferably about 70 ℃ or higher, and the lower limit temperature of the nematic phase is preferably about-10 ℃ or lower. The viscosity of the composition correlates to the response time of the element. In order to display a moving image as an element, the response time is preferably short. Ideally shorter than 1 millisecond of response time. Therefore, it is preferable that the viscosity of the composition is small. Further, it is preferable that the viscosity at low temperature is low. The elastic constant of the composition correlates to the contrast of the element. In the element, in order to improve the contrast, it is more preferable that the elastic constant of the composition is large.

The optical anisotropy of the composition correlates with the contrast of the element. Depending on the mode of the element, a large optical anisotropy or a small optical anisotropy, i.e., an appropriate optical anisotropy, is required. The product (Δ n × d) of the optical anisotropy (Δ n) of the composition and the cell gap (d) of the element is designed to maximize the contrast. The value of the appropriate product depends on the type of operation mode. In a TN-type element or the like, a suitable value is about 0.45. mu.m. In this case, a composition having a large optical anisotropy is preferable for an element having a small cell gap. The large dielectric anisotropy of the composition contributes to a low threshold voltage, small power consumption, and large contrast of the element. Therefore, a large dielectric anisotropy is preferable. The large specific resistance of the composition contributes to a large voltage holding ratio and a large contrast ratio of the element. Therefore, a composition having a large specific resistance at room temperature in the initial stage, but also at a temperature close to the upper limit temperature of the nematic phase is preferable. The composition is preferably a composition having a large specific resistance not only at room temperature but also at a temperature close to the upper limit temperature of the nematic phase after long-term use. The stability of the composition to light and heat correlates with the lifetime of the liquid crystal display element. At high stability, the lifetime of the element is long. Such characteristics are preferable for AM elements used in liquid crystal monitors, liquid crystal televisions, and the like.

A composition having positive dielectric anisotropy is used for an AM element having a TN mode. A composition having negative dielectric anisotropy is used for an AM element having a VA mode. A composition having positive or negative dielectric anisotropy is used for an AM element having an IPS mode or an FFS mode. A composition having positive or negative dielectric anisotropy is used in an AM element of a Polymer Sustained Alignment (PSA) type.

Further, these liquid crystal display elements are required to have excellent display quality in which display defects such as burn marks and display unevenness are not present or suppressed. In order to realize this, attempts have been made to improve the reliability of the entire Liquid Crystal Display (LCD) panel by adding various additives to a Liquid Crystal composition.

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent laid-open No. 2017-105762

Disclosure of Invention

[ problems to be solved by the invention ]

The invention provides a liquid crystal composition containing a compound having an effect of suppressing display defects such as line afterimages and an antistatic effect. Another object is to provide a liquid crystal composition which satisfies at least one of the characteristics of a high upper limit temperature of a nematic phase, a low lower limit temperature of the nematic phase, a low viscosity, an appropriate optical anisotropy, a large positive dielectric anisotropy, a large specific resistance, a high stability to light, a high stability to heat, and a large elastic constant. Another object is to provide a liquid crystal composition having an appropriate balance between at least two of these characteristics. Another object is to provide a liquid crystal display element containing such a composition. Another object is to provide a liquid crystal display element having excellent display quality, in which display defects such as burn marks and display unevenness are not present or suppressed by using such a composition. Still another object is to provide an AM device having characteristics such as a short response time, a high voltage holding ratio, a low threshold voltage, a high contrast ratio, and a long lifetime.

[ means for solving problems ]

The present inventors have studied various liquid crystal compounds and various chemical substances and have found that the above problems can be solved by using a specific compound, and have completed the present invention. That is, the present invention provides a liquid crystal composition containing at least one compound selected from compounds having a monovalent group represented by formula (S) as a first additive and having a nematic phase and positive dielectric anisotropy, and also provides a liquid crystal display element using the same.

In the formula (S), R^aHydrogen, O, OH, an alkyl group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms, wherein at least one-CH group₂-may be substituted by-O-, -NH-, -CO-, -COO-or-OCO-, at least one-CH₂-CH₂-may be substituted by-CH ═ CH-or-C ≡ C-, at least one of these groups may be substituted by an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, halogen, OH, NHR^1bOr NR^1cR^1dSubstitution; r^1b、R^1cAnd R^1dIs an alkyl group having 1 to 10 carbon atoms.

[ Effect of the invention ]

The present invention has an advantage of providing a liquid crystal composition containing a compound having an effect of suppressing display defects such as line afterimages and an antistatic effect. Another advantage is to provide a liquid crystal composition that sufficiently satisfies at least one of characteristics such as a high upper limit temperature of a nematic phase, a low lower limit temperature of the nematic phase, a small viscosity, a suitable optical anisotropy, a large positive dielectric anisotropy, a large specific resistance, a high stability to light, and a high stability to heat. Another advantage is to provide a liquid crystal composition having a proper balance between at least two of these characteristics. Another advantage is to provide a liquid crystal display element containing such a composition. Another advantage is to provide a liquid crystal display element having excellent display quality in which display defects such as burn marks or display unevenness are not present or suppressed. Still another advantage is to provide an AM element having characteristics such as a short response time, a large voltage holding ratio, a low threshold voltage, a large contrast ratio, and a long lifetime.

Drawings

FIG. 1A is an observation result of a line afterimage before (initial) application of a stress voltage in comparative example 1;

FIG. 1B is an observation result of a line afterimage after (after) application of a stress voltage in comparative example 1;

FIG. 2A is an observation result of a line afterimage before (initial) application of a stress voltage in example 1;

FIG. 2B is the observation result of the line afterimage after (after) the stress voltage of example 1 is applied;

FIG. 3A is an observation result of a line afterimage before (initial) application of a stress voltage in example 2;

fig. 3B is an observation result of a line residual image after (after) application of the stress voltage in example 2.

Detailed Description

The usage of the terms in the present specification is as follows. The terms "liquid crystal composition" and "liquid crystal display element" may be simply referred to as "composition" and "element", respectively. The term "liquid crystal display element" is a generic term for liquid crystal display panels and liquid crystal display modules. The "liquid crystal compound" is a general term for compounds having a liquid crystal phase such as a nematic phase or a smectic phase (smectic phase), and compounds which do not have a liquid crystal phase but are mixed in a composition for the purpose of adjusting characteristics such as a temperature range, viscosity, and dielectric anisotropy of a nematic phase. The compound has a six-membered ring such as 1, 4-cyclohexylene or 1, 4-phenylene, and the molecules (liquid crystal molecules) thereof are rod-like (rod like). The "polymerizable compound" is a compound added for the purpose of forming a polymer in the composition. The liquid crystalline compound having an alkenyl group is not classified into a polymerizable compound in terms of its meaning.

The liquid crystal composition is prepared by mixing a plurality of liquid crystalline compounds. An additive such as an optically active compound or a polymerizable compound is added to the liquid crystal composition as needed. Even in the case where an additive is added, the proportion of the liquid crystalline compound is represented by a mass percentage (mass%) based on the mass of the liquid crystal composition containing no additive. The proportion of the additive is represented by mass percentage (mass%) based on the mass of the liquid crystal composition containing no additive. That is, the ratio of the liquid crystalline compound or the additive is calculated based on the total mass of the liquid crystalline compound.

The "upper limit temperature of the nematic phase" may be simply referred to as "upper limit temperature". The "lower limit temperature of the nematic phase" may be simply referred to as "lower limit temperature". The expression "increase in dielectric anisotropy" means that the value increases positively in a composition having positive dielectric anisotropy, and increases negatively in a composition having negative dielectric anisotropy. The "large voltage holding ratio" means that the device has a large voltage holding ratio not only at room temperature but also at a temperature close to the upper limit temperature in the initial stage, and also has a large voltage holding ratio not only at room temperature but also at a temperature close to the upper limit temperature after long-term use. The properties of the composition or the element are sometimes investigated by time-varying tests.

In formula (1Z), the notation of α and β surrounded by hexagons corresponds to ring α and ring β, respectively, and represents a six-membered ring, a condensed ring, or the like, in the case where subscript 'x' is 2, two rings α are present, the two groups represented by two rings α may be the same or may be different, the rule applies to any two rings α where subscript 'x' is greater than 2, the rule also applies to other notation such as a bond group Z, a diagonal line cutting one side of ring β indicates that any hydrogen on ring β is substituted with a substituent (-Sp-P), subscript 'y' indicates the number of substituted substituents, in the case where subscript 'y' is 0, there is no such substitution, in the case where subscript 'y' is 2 or more, there are a plurality of substituents (-Sp-P) on ring β, in this case, the rule of "may be the same or may also apply, and the rule also applies to the case where a plurality of notations in Ra.

In the formula (1z), for example, the expression "Ra and Rb are an alkyl group, an alkoxy group or an alkenyl group" means that Ra and Rb are independently selected from the group consisting of an alkyl group, an alkoxy group and an alkenyl group. Here, the group represented by Ra and the group represented by Rb may be the same or may be different. The rules also apply to the case where the notation of Ra is used in a variety of compounds. The rules also apply to the case where multiple Ra's are used in one compound.

At least one compound selected from the compounds represented by the formula (1z) may be simply referred to as "compound (1 z)". The "compound (1 z)" means one compound, a mixture of two compounds, or a mixture of three or more compounds represented by the formula (1 z). The same applies to the compounds represented by the other formulae. The expression "at least one compound selected from the group consisting of the compounds represented by the formula (1z) and the formula (2 z)" means at least one compound selected from the group consisting of the compound (1z) and the compound (2 z).

The expression "at least one 'a'" means that the number of 'a's is arbitrary. The expression "at least one 'a' may be substituted with 'B' means that the position of 'a' is arbitrary when the number of 'a' is one, and the position thereof may be selected without limitation when the number of 'a' is two or more. Sometimes using "at least one-CH₂-may be substituted by-O-. In said case, -CH₂-CH₂-CH₂Can pass through non-contiguous-CH₂-conversion to-O-CH by-O-substitution₂-O-. However, there is no contiguous-CH₂-substituted by-O-. The reason is that: in said substitution-O-CH is formed₂- (peroxides).

The alkyl group of the liquid crystalline compound is linear or branched and does not include a cyclic alkyl group. Straight chain alkyls are preferred over branched alkyls. The same applies to terminal groups such as alkoxy groups and alkenyl groups. Regarding the configuration of 1, 4-cyclohexylene group-related stereo-configuration, the trans (trans) configuration is preferred over the cis (cis) configuration in order to increase the upper limit temperature. Since 2-fluoro-1, 4-phenylene is asymmetric in the left-right direction, it is present in the left (L) and right (R) directions.

The same applies to divalent groups such as tetrahydropyran-2, 5-diyl. Further, in order to raise the upper limit temperature, tetrahydropyran-2, 5-diyl (R) is preferred. The same applies to a bonding group (-COO-or-OCO-) such as carbonyloxy.

The present invention is as follows.

Item 1. a liquid crystal composition containing at least one compound selected from the group consisting of compounds having a monovalent group represented by the formula (S) as a first additive, and having a nematic phase and positive dielectric anisotropy.

In the formula (S), R^aHydrogen, O, OH, an alkyl group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms, wherein at least one-CH group₂-may be substituted by-O-, -NH-, -CO-, -COO-or-OCO-, at least one-CH₂-CH₂-may be substituted by-CH ═ CH-or-C ≡ C-, at least one of these groups may be substituted by an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, halogen, OH, NHR^1bOr NR^1cR^1dSubstitution; r^1b、R^1cAnd R^1dIs an alkyl group having 1 to 10 carbon atoms.

Item 2. the liquid crystal composition according to item 1, which contains at least one compound selected from the compounds represented by formula (1) as a first additive.

In the formula (1), the reaction mixture is,R^bis hydrogen, fluorine, an alkyl group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms, wherein at least one of the groups-CH₂-may be substituted by-O-, -NH-, -CO-, -COO-or-OCO-, at least one-CH₂-CH₂-may be substituted by-CH ═ CH-or-C ≡ C-, at least one of these groups may be substituted by an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, halogen, OH, NHR^1bOr NR^1cR^1dSubstitution; r^1b、R^1cAnd R^1dAn alkyl group having 1 to 10 carbon atoms; m is a single bond, a tetravalent aliphatic hydrocarbon group having 1 to 20 carbon atoms, or a tetravalent aromatic hydrocarbon group having 6 to 20 carbon atoms, wherein at least one of these groups is-CH₂-may be substituted by-O-or-S-, one or two-CH ═ CH-may be substituted by-CH ═ N-, at least one hydrogen may be substituted by fluorine or chlorine; z^aAnd Z^bA single bond, -O-, -COO-, -OCO-, an alkylene group having 1 to 20 carbon atoms, or an alkenylene group having 2 to 20 carbon atoms, wherein at least one hydrogen may be substituted by fluorine, chlorine, OH; q^aA monovalent group represented by the formula (S); n is 1, 2,3 or 4; m is 4-n; wherein, when M is a single bond, n and M are 1;

in the formula (S), R^aHydrogen, O, OH, an alkyl group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms, wherein at least one-CH group₂-may be substituted by-O-, -NH-, -CO-, -COO-or-OCO-, at least one-CH₂-CH₂-may be substituted by-CH ═ CH-or-C ≡ C-, at least one of these groups may be substituted by an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, halogen, OH, NHR^1bOr NR^1cR^1dSubstitution; r^1b、R^1cAnd R^1dIs an alkyl group having 1 to 10 carbon atoms.

Item 3. the liquid crystal composition according to item 1 or item 2, which contains at least one compound selected from the group consisting of the compounds represented by formulae (1-1) to (1-5) as a first additive.

In formulae (1-1) to (1-5), Z^cA single bond, an alkylene group having 1 to 5 carbon atoms, or an alkenylene group having 2 to 5 carbon atoms, at least one hydrogen of which may be substituted with OH; r^cHydrogen, an alkyl group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms, wherein at least one-CH group₂-may be substituted by-O-, -CO-, -COO-or-OCO-, at least one-CH₂-CH₂-may be substituted with-CH ═ CH-or-C ≡ C-, at least one hydrogen of these groups may be substituted with OH, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms; s is an integer from 1 to 20; q^bIs a monovalent group represented by the formula (S-1);

in the formula (S-1), R^dHydrogen, O, OH, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms, wherein at least one hydrogen may be substituted with a halogen.

Item 4. the liquid crystal composition according to any one of item 1 to item 3, wherein a proportion of the first additive is in a range of 0.001% by mass to 2% by mass.

Item 5. the liquid crystal composition according to any one of item 1 to item 4, which contains at least one compound selected from the compounds represented by formula (2) as a first component.

In the formula (2), R^2aIs alkyl group having 1 to 12 carbon atoms, alkoxy group having 1 to 12 carbon atoms, or alkenyl group having 2 to 12 carbon atoms; ring a is 1, 4-cyclohexylene, 1, 4-phenylene, 2-fluoro-1, 4-phenylene, 2, 3-difluoro-1, 4-phenylene, 2, 6-difluoro-1, 4-phenylene, pyrimidine-2, 5-diyl, 1, 3-dioxane-2, 5-diyl or tetrahydropyran-2, 5-diyl; z^2aIs a single bond, ethylene, vinylene, carbonyloxy or difluoromethyleneoxy; x^2aAnd X^2bIs hydrogen or fluorine; y is^2aIs fluorine, chlorine, alkyl of carbon number 1 to 12 with at least one hydrogen substituted by fluorine or chlorine, alkoxy of carbon number 1 to 12 with at least one hydrogen substituted by fluorine or chlorine, or alkenyloxy of carbon number 2 to 12 with at least one hydrogen substituted by fluorine or chlorine; a is 1, 2,3 or 4.

Item 6. the liquid crystal composition according to any one of item 1 to item 5, which contains at least one compound selected from the group consisting of the compounds represented by formulae (2-1) to (2-35) as a first component.

In the formulae (2-1) to (2-35), R^2aIs an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or an alkenyl group having 2 to 12 carbon atoms.

Item 7. the liquid crystal composition according to item 5 or item 6, wherein the proportion of the first component is in a range of 10% by mass to 85% by mass.

Item 8. the liquid crystal composition according to any one of item 1 to item 7, which contains at least one compound selected from the compounds represented by formula (3) as a second component.

In the formula (3), R^3aAnd R^3bIs alkyl group having 1 to 12 carbon atoms, alkoxy group having 2 to 12 carbon atoms12 alkenyl or alkenyl of carbon number 2 to 12 in which at least one hydrogen is substituted by fluorine or chlorine; ring B and ring C are 1, 4-cyclohexylene, 1, 4-phenylene, 2-fluoro-1, 4-phenylene or 2, 5-difluoro-1, 4-phenylene; z^3aIs a single bond, ethylene, vinylidene, methyleneoxy or carbonyloxy; b is 1, 2 or 3.

Item 9. the liquid crystal composition according to any one of item 1 to item 8, which contains at least one compound selected from the group consisting of the compounds represented by formulae (3-1) to (3-13) as the second component.

In formulae (3-1) to (3-13), R^3aAnd R^3bIs an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, or an alkenyl group having 2 to 12 carbon atoms in which at least one hydrogen is substituted with fluorine or chlorine.

Item 10 the liquid crystal composition according to item 8 or item 9, wherein the proportion of the second component is in a range of 10% by mass to 85% by mass.

Item 11. the liquid crystal composition according to any one of item 1 to item 10, which contains at least one compound selected from the compounds represented by formula (4) as a third component.

In the formula (4), R^4aAnd R^4bIs hydrogen, alkyl group having 1 to 12 carbon atoms, alkoxy group having 1 to 12 carbon atoms, alkenyl group having 2 to 12 carbon atoms, or alkenyloxy group having 2 to 12 carbon atoms; ring D and ring F are 1, 4-cyclohexylene, 1, 4-cyclohexenylene, tetrahydropyran-2, 5-diyl, 1, 4-phenylene in which at least one hydrogen is substituted by fluorine or chlorine, naphthalene-2, 6-diyl in which at least one hydrogen is substituted by fluorine or chlorine, chroman-2, 6-diyl in which at least one hydrogen is substituted by fluorine or chlorine, or chroman-2, 6-diyl in which at least one hydrogen is substituted by fluorine or chlorine; ring E is 2, 3-difluoro-1, 4-phenylene, 2-chloro-3-fluoro-1, 4-phenylene, 2, 3-difluoro-5-methyl-1, 4-phenylene, 3,4, 5-trifluoronaphthalene-2, 6-diyl, 7, 8-difluorochromane-2, 6-diyl, a salt thereof, a hydrate,3,4,5, 6-tetrafluorofluorene-2, 7-diyl, 4, 6-difluorodibenzofuran-3, 7-diyl, 4, 6-difluorodibenzothiophene-3, 7-diyl, or 1,1,6, 7-tetrafluoroindan-2, 5-diyl; z^4aAnd Z^4bIs a single bond, ethylene, vinylidene, methyleneoxy or carbonyloxy; c is 0, 1, 2 or 3, d is 0 or 1; and the sum of c and d is 3 or less.

Item 12. the liquid crystal composition according to any one of items 1 to 11, which contains at least one compound selected from the group consisting of the compounds represented by formulae (4-1) to (4-35) as a third component.

In the formulae (4-1) to (4-35), R^4aAnd R^4bIs hydrogen, alkyl group having 1 to 12 carbon atoms, alkoxy group having 1 to 12 carbon atoms, alkenyl group having 2 to 12 carbon atoms, or alkenyloxy group having 2 to 12 carbon atoms.

Item 13. the liquid crystal composition of item 11 or item 12, wherein the proportion of the third component is in a range of 3 to 45 mass%.

Item 14. the liquid crystal composition according to any one of item 1 to item 13, wherein the upper limit temperature of the nematic phase is 70 ℃ or more, the optical anisotropy at a wavelength of 589nm (measured at 25 ℃) is 0.07 or more, and the dielectric anisotropy at a frequency of 1kHz (measured at 25 ℃) is 2 or more.

An item 15. a liquid crystal display element containing the liquid crystal composition according to any one of items 1 to 14.

Item 16. the liquid crystal display device of item 15, wherein the liquid crystal display device operates in a TN mode, an ECB mode, an OCB mode, an IPS mode, an FFS mode, or an FPA mode, and the liquid crystal display device is driven in an active matrix mode.

Item 17. use of a liquid crystal composition according to any one of items 1 to 14 for a liquid crystal display element.

The present invention also includes the following items. (a) The composition contains one compound, two compounds or three or more compounds selected from additives such as an optically active compound, an antioxidant, an ultraviolet absorber, a delustering agent, a pigment, an antifoaming agent, a polymerizable compound, a polymerization initiator and a polymerization inhibitor. (b) An AM element comprising the composition. (c) The composition further contains a polymerizable compound, and a polymer-stabilized oriented (PSA) AM element containing the composition. (d) An AM element of Polymer Stable Alignment (PSA) type, comprising the composition, wherein a polymerizable compound in the composition is polymerized. (e) An element comprising said composition and having a pattern of PC, TN, STN, ECB, OCB, IPS, VA, FFS or FPA. (f) A permeable element comprising the composition. (g) Use of said composition as a composition having a nematic phase. (h) Use of an optically active composition obtained by adding an optically active compound to the composition.

The composition of the present invention is illustrated in the following order. First, the composition of the component compounds in the composition will be described. Second, the main characteristics of the component compounds and the main effects of the compounds on the composition or element will be described. Third, the combination of the component compounds in the composition, the preferable ratio of the component compounds, and the basis thereof will be described. Fourth, preferred embodiments of the component compounds will be described. Fifth, preferred component compounds are shown. Sixth, additives that can be added to the composition will be described. Seventh, a method for synthesizing the component compound will be explained. Finally, the use of the composition is illustrated.

First, the composition of the component compounds in the composition will be described. The composition contains a plurality of liquid crystalline compounds. The composition may also contain additives. The additive is an optically active compound, an antioxidant, an ultraviolet absorber, a matting agent, a coloring matter, an antifoaming agent, a polymerizable compound, a polymerization initiator, a polymerization inhibitor, a polar compound, or the like. From the viewpoint of the liquid crystalline compound, the compositions are classified into composition a and composition B. The composition a may contain other liquid crystalline compounds, additives, and the like in addition to the liquid crystalline compound selected from the compound (2), the compound (3), and the compound (4). The "other liquid crystalline compound" is a liquid crystalline compound different from the compound (2), the compound (3) and the compound (4). Such compounds are mixed in the composition for the purpose of further adjusting the properties.

The composition B substantially contains only a liquid crystalline compound selected from the group consisting of the compound (2), the compound (3) and the compound (4). "substantially" means that the composition B may contain additives but does not contain other liquid crystalline compounds. The amount of ingredients of composition B is low compared to composition a. From the viewpoint of cost reduction, composition B is superior to composition a. From the viewpoint that the properties can be further adjusted by mixing other liquid crystalline compounds, the composition a is superior to the composition B.

Second, the main characteristics of the component compounds and the main effects of the compounds on the composition or element will be described. The main properties of the component compounds based on the effects of the present invention are summarized in Table 2. In the notation of Table 2, L means large or high, M means medium, and S means small or low. The notation L, M, S is a classification based on qualitative comparisons between component compounds, with notation 0 (zero) meaning smaller than S.

TABLE 2 Properties of liquid crystalline Compounds

Characteristics of	Compound (2)	Compound (3)	Compound (4)
				Upper limit temperature	S～L	S～L	S～L
Viscosity of the oil	M～L	S～M	L
				Optical anisotropy	M～L	S～L	M～L
Dielectric anisotropy	S～L	0	M～L1)
				Specific resistance	L	L	L

1) The dielectric anisotropy is negative, and the notation indicates the magnitude of the absolute value.

The main effects of the component compounds are as follows. The first additive functions as a display defect inhibitor such as burn marks and display unevenness. Since the amount of the compound (1) added is small, the properties such as the upper limit temperature, the optical anisotropy and the dielectric anisotropy are not affected in many cases. The compound (2) increases the dielectric anisotropy and lowers the lower limit temperature. The compound (3) lowers the viscosity or raises the upper limit temperature. The compound (4) increases the dielectric constant in the minor axis direction.

The display quality may be significantly reduced by long-term use of the liquid crystal display element. As one of the factors, consider the following case: when the liquid crystal composition is driven for a long period of time, a small amount of inherently charged particles in the liquid crystal composition are unevenly concentrated, or potential is accumulated between an element member other than the liquid crystal composition and the liquid crystal composition for some reason, and display defects such as burning marks of display and display unevenness occur.

The first additive of the present invention is at least one compound selected from compounds having a monovalent group represented by formula (S). By adding the compound, the electric resistance of the liquid crystal display element can be extremely reduced without greatly reducing the specific resistance value of the liquid crystal composition. The amino group site of the compound is attracted to an adsorption site (for example, a carbonyl group located on the surface of the alignment film) of the peripheral material of the LCD panel, forming an adsorption layer. The layer has a low resistance value, thereby suppressing the deflection of charged particles and the accumulation of potential, and suppressing display defects such as burn marks and display unevenness. And functions as a so-called local antistatic agent.

Third, the combination of the component compounds in the composition, the preferable ratio of the component compounds, and the basis thereof will be described. Preferred combinations of the component compounds in the composition are the first additive + compound (2), the first additive + compound (3), the first additive + compound (2) + compound (4), the first additive + compound (3) + compound (4), the first additive + compound (2) + compound (3) + compound (4). Further preferred combinations are the first additive plus compound (2) + compound (3) or the first additive plus compound (2) + compound (3) + compound (4).

The preferable proportion of the first additive is about 0.001 mass% or more, and the preferable proportion of the first additive is about 2 mass% or less in order to lower the lower limit temperature. Further, the preferable ratio is in the range of about 0.010 mass% to about 1.000 mass%. A particularly preferred ratio is in the range of about 0.020% by mass to about 0.150% by mass.

The preferable proportion of the compound (2) is about 10% by mass or more for improving the dielectric anisotropy, and the preferable proportion of the compound (2) is about 85% by mass or less for lowering the lower limit temperature or for lowering the viscosity. Further, the preferable ratio is in the range of about 20 to about 80 mass%. A particularly preferred ratio is in the range of about 30 to about 70 mass%.

The preferable proportion of the compound (3) is about 10% by mass or more in order to increase the upper limit temperature or to decrease the viscosity, and the preferable proportion of the compound (3) is about 85% by mass or less in order to increase the dielectric anisotropy. Further, the preferable ratio is in the range of about 20 to about 80 mass%. A particularly preferred ratio is in the range of about 25% to about 70% by mass.

The preferable proportion of the compound (4) is about 3% by mass or more in order to increase the dielectric constant in the short axis direction, and the preferable proportion of the compound (4) is about 45% by mass or less in order to lower the lower limit temperature. Further, the preferable ratio is in the range of about 5% by mass to about 40% by mass. A particularly preferred ratio is in the range of about 5% to about 35% by mass.

Fourth, preferred embodiments of the component compounds will be described. In the formula (1), R^bIs hydrogen, fluorine, an alkyl group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms, wherein at least one of the groups-CH₂-may be substituted by-O-, -NH-, -CO-, -COO-or-OCO-, at least one-CH₂-CH₂-may be substituted by-CH ═ CH-or-C ≡ C-, at least one of these groups may be substituted by an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, halogen, OH, NHR^1bOr NR^1cR^1dAnd (4) substitution. R^1b、R^1cAnd R^1dIs an alkyl group having 1 to 10 carbon atoms. Preferred R^bHydrogen, an alkyl group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 6 to 15 carbon atoms, and an aromatic hydrocarbon group having 6 to 15 carbon atoms. Preferred R^1b、R^1cOr R^1dIs an alkyl group having 1 to 5 carbon atoms. M is a single bond, a tetravalent aliphatic hydrocarbon group having 1 to 20 carbon atoms, or a tetravalent aromatic hydrocarbon group having 6 to 20 carbon atoms, wherein at least one of these groups is-CH₂-may be substituted by-O-or-S-, one or two-CH ═ CH-may be substituted by-CH ═ N-, at least one hydrogen may be substituted by fluorine or chlorine. Preferably, M is a tetravalent aliphatic hydrocarbon group having 1 to 10 carbon atoms or a tetravalent aromatic hydrocarbon group having 6 to 10 carbon atoms. Z^aAnd Z^bIs a single bond, -O-, -COO-, -OCO-, an alkylene group having 1 to 20 carbon atoms, or an alkenylene group having 2 to 20 carbon atoms, and at least one hydrogen of these groups may be substituted by fluorine, chlorine, or OH. Preferred Z^aOr Z^bIs a single bond, -COO-, -OCO-, or alkylene having 1 to 5 carbon atoms. Q^aIs a monovalent group represented by the formula (S). n is 1, 2,3 or 4; m is 4-n. Preferably n is 2 or 4.

In the formula (S), R^aHydrogen, O, OH, an alkyl group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms, wherein at least one-CH group₂-may be substituted by-O-, -NH-, -CO-, -COO-or-OCO-, at least one-CH₂-CH₂-may be substituted by-CH ═ CH-or-C ≡ C-, at least one of these groups may be substituted by an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, halogen, OH, NHR^1bOr NR^1cR^1dAnd (4) substitution. R^1b、R^1cAnd R^1dIs an alkyl group having 1 to 10 carbon atoms. Preferred R^aIs methyl. Preferred R^1b、R^1cOr R^1dIs an alkyl group having 1 to 5 carbon atoms.

In formulae (1-1) to (1-5), Z^cIs a single bond, an alkylene group having 1 to 5 carbon atoms, or an alkenylene group having 2 to 5 carbon atoms, and at least one hydrogen of these groups may be substituted with OH. Preferred Z^cIs a single bond, methylene or ethylene. R^cHydrogen, an alkyl group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms, wherein at least one-CH group₂May be via-O-, -CO-, -COO-or-OCO-substitution of at least one-CH₂-CH₂-may be substituted with-CH ═ CH-or-C ≡ C-, and of these, at least one hydrogen may be substituted with OH, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms. Preferred R^cIs an aromatic hydrocarbon group having 6 to 10 carbon atoms or an aromatic hydrocarbon group having 6 to 10 carbon atoms in which at least one hydrogen is substituted with OH. s is an integer from 1 to 20. Preferably s is an integer from 1 to 8. Q^bIs a monovalent group represented by the formula (S-1).

Here, R^dHydrogen, O, OH, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms, wherein at least one hydrogen may be substituted with a halogen. Preferred R^dIs methyl.

Representative examples of the first additive are shown below, but the present invention is not limited to these examples.

In the formulae (2), (3) and (4), R^2aIs an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or an alkenyl group having 2 to 12 carbon atoms. Preferred R is for improving stability to light or heat^2aIs an alkyl group having 1 to 12 carbon atoms. R^3aAnd R^3bIs an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, or an alkenyl group having 2 to 12 carbon atoms in which at least one hydrogen is substituted with fluorine or chlorine. Preferred R for reducing viscosity^3aOr R^3bR is an alkenyl group having 2 to 12 carbon atoms, and is preferably selected from the group consisting of^3aOr R^3bIs an alkyl group having 1 to 12 carbon atoms. R^4aAnd R^4bIs hydrogen, alkyl group having 1 to 12 carbon atoms, alkoxy group having 1 to 12 carbon atoms, alkenyl group having 2 to 12 carbon atoms, or alkenyloxy group having 2 to 12 carbon atoms. Preferred R is for improving stability to light or heat^4aOr R^4bIs alkyl group having 1 to 12 carbon atoms for improving dielectric anisotropyPreferred is R^4aOr R^4bIs alkoxy with 1 to 12 carbon atoms.

Preferred alkyl groups are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl or octyl. Further preferred alkyl groups for reducing the viscosity are methyl, ethyl, propyl, butyl or pentyl.

Preferred alkoxy groups are methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy or heptoxy. Further preferred alkoxy groups for reducing the viscosity are methoxy or ethoxy.

Preferred alkenyl groups are vinyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl or 5-hexenyl. Further preferred alkenyl groups for reducing the viscosity are vinyl, 1-propenyl, 3-butenyl or 3-pentenyl. The preferred steric configuration of-CH ═ CH-in these alkenyl groups depends on the position of the double bond. Among alkenyl groups such as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl, 3-pentenyl, 3-hexenyl, the trans-form is preferable from the viewpoint of reducing viscosity and the like. Among alkenyl groups such as 2-butenyl, 2-pentenyl, 2-hexenyl, cis-form is preferred.

Preferred alkenyloxy groups are vinyloxy, allyloxy, 3-butenyloxy, 3-pentenyloxy or 4-pentenyloxy. Further preferred alkenyloxy groups are allyloxy or 3-butenyloxy groups in order to reduce the viscosity.

Preferred examples of alkyl groups in which at least one hydrogen is replaced by fluorine or chlorine are fluoromethyl, 2-fluoroethyl, 3-fluoropropyl, 4-fluorobutyl, 5-fluoropentyl, 6-fluorohexyl, 7-fluoroheptyl or 8-fluorooctyl. Further preferable examples of the compound include 2-fluoroethyl, 3-fluoropropyl, 4-fluorobutyl and 5-fluoropentyl for improving the dielectric anisotropy.

Preferred examples of alkenyl groups in which at least one hydrogen is substituted by fluorine or chlorine are 2, 2-difluorovinyl, 3-difluoro-2-propenyl, 4-difluoro-3-butenyl, 5-difluoro-4-pentenyl or 6, 6-difluoro-5-hexenyl. Further preferable examples for lowering the viscosity are 2, 2-difluorovinyl group and 4, 4-difluoro-3-butenyl group.

Ring a is 1, 4-cyclohexylene, 1, 4-phenylene, 2-fluoro-1, 4-phenylene, 2, 3-difluoro-1, 4-phenylene, 2, 6-difluoro-1, 4-phenylene, pyrimidine-2, 5-diyl, 1, 3-dioxane-2, 5-diyl or tetrahydropyran-2, 5-diyl. In order to improve the optical anisotropy, ring A is preferably 1, 4-phenylene or 2-fluoro-1, 4-phenylene. Tetrahydropyran-2, 5-diyl as

Preferably, it is

The ring B and the ring C are 1, 4-cyclohexylene, 1, 4-phenylene, 2-fluoro-1, 4-phenylene or 2, 5-difluoro-1, 4-phenylene. The ring B or C is preferably a 1, 4-cyclohexylene group for lowering the viscosity, and a 1, 4-phenylene group for improving the optical anisotropy. Ring D and ring F are 1, 4-cyclohexylene, 1, 4-cyclohexenylene, tetrahydropyran-2, 5-diyl, 1, 4-phenylene in which at least one hydrogen is substituted by fluorine or chlorine, naphthalene-2, 6-diyl in which at least one hydrogen is substituted by fluorine or chlorine, chroman-2, 6-diyl in which at least one hydrogen is substituted by fluorine or chlorine, or chroman-2, 6-diyl in which at least one hydrogen is substituted by fluorine or chlorine. Preferred examples of "1, 4-phenylene in which at least one hydrogen is substituted by fluorine or chlorine" are 2-fluoro-1, 4-phenylene, 2, 3-difluoro-1, 4-phenylene or 2-chloro-3-fluoro-1, 4-phenylene. The ring D or F is preferably a 1, 4-cyclohexylene group for lowering the viscosity, a tetrahydropyran-2, 5-diyl group for improving the dielectric anisotropy, and a 1, 4-phenylene group for improving the optical anisotropy. Ring E is 2, 3-difluoro-1, 4-phenylene, 2-chloro-3-fluoro-1, 4-phenylene, 2, 3-difluoro-5-methyl-1, 4-phenylene, 3,4, 5-trifluoronaphthalene-2, 6-diyl, 7, 8-difluorochromane-2, 6-diyl, 3,4,5, 6-tetrafluorofluorene-2, 7-diyl (FLF4), 4, 6-difluorodibenzofuran-3, 7-diyl (DBTF2), 4, 6-difluorodibenzothiophene-3, 7-diyl (DBTF2), or 1,1,6, 7-tetrafluoroindan-2, 5-diyl (InF 4).

The preferred ring E is 2, 3-difluoro-1, 4-phenylene for decreasing viscosity, 2-chloro-3-fluoro-1, 4-phenylene for decreasing optical anisotropy, and 7, 8-difluorochroman-2, 6-diyl for increasing dielectric anisotropy.

Z^2aIs a single bond, ethylene, vinylene, carbonyloxy or difluoromethyleneoxy. For reducing the viscosity, preferred is Z^2aIs a single bond, and Z is preferably a bond for improving dielectric anisotropy^2aIs difluoromethyleneoxy. Z^3aIs a single bond, ethylene, vinylidene, methyleneoxy or carbonyloxy. For reducing the viscosity, preferred is Z^3aIs a single bond. Z^4aAnd Z^4bIs a single bond, ethylene, vinylidene, methyleneoxy or carbonyloxy. For reducing the viscosity, preferred is Z^4aOr Z^4bIs a single bond, and Z is preferably Z for lowering the lower limit temperature^4aOr Z^4bIs ethylene, and Z is preferably selected to improve the dielectric anisotropy^4aOr Z^4bIs methyleneoxy.

Divalent groups such as methyleneoxy groups are asymmetric in the left-right direction. In the methyleneoxy group, -CH₂O-is superior to-OCH₂-. In the carbonyloxy group, -COO-is preferable to-OCO-. Of difluoromethyleneoxy, -CF₂O-is superior to-OCF₂-。

X^2aAnd X^2bIs hydrogen or fluorine. For improving the dielectric anisotropy, X is preferable^2aOr X^2bIs fluorine.

Y^2aIs fluorine, chlorine, alkyl of carbon number 1 to 12 with at least one hydrogen substituted by fluorine or chlorine, alkoxy of carbon number 1 to 12 with at least one hydrogen substituted by fluorine or chlorine, or alkenyloxy of carbon number 2 to 12 with at least one hydrogen substituted by fluorine or chlorine. For lowering the lower limit temperature, Y is preferable^2aIs fluorine.

A preferred example of an alkyl group in which at least one hydrogen is substituted by fluorine or chlorine is trifluoromethyl. A preferred example of an alkoxy group wherein at least one hydrogen is substituted by fluorine or chlorine is trifluoromethoxy. A preferred example of an alkenyloxy group substituted by at least one hydrogen with fluorine or chlorine is trifluoroethylenyloxy.

a is 1, 2,3 or 4. In order to lower the lower limit temperature, a is preferably 2, and in order to improve the dielectric anisotropy, a is preferably 3. b is 1, 2 or 3. For lowering the viscosity, b is preferably 1, and for raising the upper limit temperature, b is preferably 2 or 3. c is 0, 1, 2 or 3, d is 0 or 1, and the sum of c and d is 3 or less. For lowering the viscosity, c is preferably 1, and for raising the upper limit temperature, c is preferably 2 or 3. For lowering the viscosity, d is preferably 0, and for lowering the lower limit temperature, d is preferably 1.

Fifth, preferred component compounds are shown. Preferred compound (1) is the compound (1-1) to the compound (1-5) described in the item 3. Among these compounds, the compound (1-1) or the compound (1-2) is preferable.

Preferred compound (2) is the compound (2-1) to the compound (2-35) described in the item 6. Of these compounds, it is preferable that at least one of the first components is compound (2-4), compound (2-12), compound (2-14), compound (2-15), compound (2-17), compound (2-18), compound (2-23), compound (2-24), compound (2-27), compound (2-29) or compound (2-30). Preferably, at least two of the first components are a combination of the compound (2-12) and the compound (2-15), the compound (2-14) and the compound (2-27), the compound (2-18) and the compound (2-24), the compound (2-18) and the compound (2-29), the compound (2-24) and the compound (2-29), or the compound (2-29) and the compound (2-30).

Preferred compound (3) is the compound (3-1) to the compound (3-13) described in the item 9. Of these compounds, it is preferable that at least one of the second components is compound (3-1), compound (3-3), compound (3-5), compound (3-6) or compound (3-7). Preferably, at least two of the second components are a combination of the compound (3-1) and the compound (3-5), the compound (3-1) and the compound (3-6), the compound (3-1) and the compound (3-7), the compound (3-3) and the compound (3-5), the compound (3-3) and the compound (3-6), and the compound (3-3) and the compound (3-7).

Preferred compound (4) is the compound (4-1) to the compound (4-35) described in the item 12. Of these compounds, it is preferable that at least one of the third components is the compound (4-1), the compound (4-3), the compound (4-6), the compound (4-8), the compound (4-10), the compound (4-14) or the compound (4-16). Preferably, at least two of the third components are a combination of the compound (4-1) and the compound (4-8), the compound (4-1) and the compound (4-14), the compound (4-3) and the compound (4-8), the compound (4-3) and the compound (4-14), the compound (4-3) and the compound (4-16), the compound (4-6) and the compound (4-8), the compound (4-6) and the compound (4-10), the compound (4-6) and the compound (4-16), the compound (4-10) and the compound (4-16).

Sixth, additives that can be added to the composition will be described. Such additives include optically active compounds, antioxidants, ultraviolet absorbers, delustering agents, pigments, antifoaming agents, polymerizable compounds, polymerization initiators, polymerization inhibitors, polar compounds, and the like. An optically active compound is added to the composition for the purpose of inducing a helical structure of liquid crystal molecules to impart a twist angle (torsion angle). Examples of such compounds are compound (5-1) to compound (5-5). The preferable proportion of the optically active compound is about 5% by mass or less. Further, the preferable ratio is in the range of about 0.01 to about 2 mass%.

In order to prevent a decrease in specific resistance due to heating in the atmosphere or to maintain a large voltage holding ratio at room temperature and at a temperature close to the upper limit temperature even after the device is used for a long time, an antioxidant such as the compounds (6-1) to (6-3) may be further added to the composition.

Since the compound (6-2) has low volatility, it is effective for maintaining a large voltage holding ratio not only at room temperature but also at a temperature close to the upper limit temperature after the device is used for a long time. In order to obtain the above effect, the preferable ratio of the antioxidant is about 50ppm or more, and in order not to lower the upper limit temperature or to raise the lower limit temperature, the preferable ratio of the antioxidant is about 600ppm or less. Even more preferred ratios range from about 100ppm to about 300 ppm.

Preferable examples of the ultraviolet absorber include benzophenone derivatives, benzoate derivatives, triazole derivatives and the like. Light stabilizers such as sterically hindered amines are also preferred. Preferable examples of the light stabilizer are compound (7-1) to compound (7-16) and the like. The preferable proportion of these absorbents or stabilizers is about 50ppm or more in order to obtain the above effects, and about 10000ppm or less in order not to lower the upper limit temperature or not to raise the lower limit temperature. Even more preferred ratios range from about 100ppm to about 10000 ppm.

The matting agent is a compound that receives light energy absorbed by the liquid crystalline compound and converts the light energy into thermal energy to prevent decomposition of the liquid crystalline compound. Preferable examples of the matting agent are a compound (8-1) to a compound (8-7), and the like. The preferred proportion of these matting agents is about 50ppm or more for obtaining the above-mentioned effects, and about 20000ppm or less for lowering the lower limit temperature. Even more preferred ratios range from about 100ppm to about 10000 ppm.

Dichroic dyes (dichromatic dye) such as azo-based dyes and anthraquinone-based dyes are added to the composition in order to be suitable for guest-host (GH) mode elements. The preferable ratio of the pigment ranges from about 0.01% by mass to about 10% by mass. In order to prevent bubbling, an antifoaming agent such as dimethylsilicone oil or methylphenylsilicone oil is added to the composition. The preferable ratio of the defoaming agent is about 1ppm or more in order to obtain the above effects, and about 1000ppm or less in order to prevent display failure. Even more preferred ratios range from about 1ppm to about 500 ppm.

In order to be suitable for a Polymer Stabilized Alignment (PSA) type device, a polymerizable compound is added to the composition. Preferable examples of the polymerizable compound include compounds such as acrylic acid esters, methacrylic acid esters, vinyl compounds, vinyloxy compounds, propenyl ethers, epoxy compounds (oxetane and oxetane) and vinyl ketones. Further preferable examples are derivatives of acrylic acid esters or methacrylic acid esters. In order to obtain the above-mentioned effects, the preferable ratio of the polymerizable compound is about 0.05% by mass or more, and in order to prevent the display failure, the preferable ratio of the polymerizable compound is about 10% by mass or less. Further, the preferable ratio is in the range of about 0.1% by mass to about 2% by mass. The polymerizable compound is polymerized by ultraviolet irradiation. The polymerization may be carried out in the presence of an initiator such as a photopolymerization initiator. Suitable conditions for carrying out the polymerization, suitable types of initiators, and suitable amounts are known to those skilled in the art and are described in the literature. For example, brilliant good solid (Irgacure)651 (registered trademark; Basf), brilliant good solid (Irgacure)184 (registered trademark; Basf), or Delocur (Darocur)1173 (registered trademark; Basf) as a photopolymerization initiator is suitable for radical polymerization. The preferable proportion of the photopolymerization initiator ranges from about 0.1% by mass to about 5% by mass based on the mass of the polymerizable compound. Further, the preferable ratio is in the range of about 1% by mass to about 3% by mass.

When the polymerizable compound is stored, a polymerization inhibitor may be added to prevent polymerization. The polymerizable compound is usually added to the composition in a state where the polymerization inhibitor is not removed. Examples of the polymerization inhibitor are hydroquinone, hydroquinone derivatives such as methyl hydroquinone, 4-t-butyl catechol, 4-methoxyphenol, phenothiazine and the like.

The polar compound is an organic compound having polarity. Here, a compound having an ionic bond is not included. Atoms such as oxygen, sulfur and nitrogen are electrically negatively biased and have a tendency to have a partial negative chargeAnd (3) direction. Carbon and hydrogen are neutral or tend to have a partial positive charge. Polarity arises because part of the charge is distributed unequally among the atoms of different species in the compound. For example, the polar compound has-OH, -COOH, -SH, -NH₂、>NH、>N-, or the like.

Seventh, a method for synthesizing the component compound will be explained. These compounds can be synthesized using known methods. A synthesis method is exemplified. Compound (1-A) is available from Tokyo Chemical Industry (TCI). Compound (2-4) is synthesized by the method described in Japanese patent laid-open No. Hei 10-204016. The compound (3-1) is synthesized by the method described in Japanese patent laid-open publication No. 59-176221. The compound (4-1) is synthesized by the method described in Japanese patent laid-open No. 2000-053602. Antioxidants are already commercially available. The compound of formula (6) wherein n is 1 is available from Sigma Aldrich Corporation. The compound (6) wherein n is 7 and the like is synthesized by the method described in the specification of U.S. Pat. No. 3660505.

Compounds not described in the synthesis method can be synthesized by the method described in the following protocol: organic Synthesis (Organic Syntheses, John Wiley & Sons, Inc), "Organic Reactions (Organic Reactions, John Wiley & Sons, Inc)," Comprehensive Organic Synthesis (perhennic Synthesis, pegman Press), new experimental chemistry lecture (pill-good), and the like. The compositions are prepared from the compounds obtained in the manner described, using known methods. For example, the component compounds are mixed and then dissolved in each other by heating.

Finally, the use of the composition is illustrated. The composition has a major amount of optical anisotropy having a lower temperature limit of about-10 ℃ or less, an upper temperature limit of about 70 ℃ or more, and a range of about 0.07 to about 0.20. A composition having an optical anisotropy in the range of about 0.08 to about 0.25 may be prepared by controlling the ratio of the component compounds, or by mixing other liquid crystalline compounds. Compositions having optical anisotropy in the range of about 0.10 to about 0.30 may also be prepared by trial and error. The device containing the composition has a large voltage holding ratio. The composition is suitable for AM elements. The composition is particularly suitable for transmissive AM elements. The composition can be used as a composition having a nematic phase, and can be used as an optically active composition by adding an optically active compound.

The composition can be used in AM elements. And can also be used for PM elements. The composition can be used for AM elements and PM elements having modes such as PC, TN, STN, ECB, OCB, IPS, FFS, VA, FPA and the like. Particularly preferred is an AM element for use in a TN, OCB, IPS mode or FFS mode. In an AM element having an IPS mode or an FFS mode, when no voltage is applied, the alignment of liquid crystal molecules may be parallel or may also be perpendicular with respect to a glass substrate. These elements may be reflective, transmissive or transflective. Preferably for use in transmissive devices. It can also be used for an amorphous silicon-TFT element or a polysilicon-TFT element. The composition may be used for a device of a Nematic Curvilinear Aligned Phase (NCAP) type prepared by microencapsulation (microencapsulation) or a device of a Polymer Dispersed (PD) type in which a three-dimensional network polymer is formed in the composition.